A brake system of this type is disclosed in WO 2011/029812 A1. It is felt that a serious disadvantage of the previously known brake system is the fact that in the event of a failure of the control or of the actuation of the electrically controllable pressure source the function of the brake system in the “brake-by-wire” operating mode is not available.
It is therefore the object of the present invention to improve a brake system of the type mentioned in the introduction to the effect that even in the event of a failure of the electrically controllable pressure source or a component thereof, a brake-by-wire function continues to be available.